SINGAPORE (Reuters) - Singapore and Malaysia vowed on Tuesday to push ahead with two ambitious rail projects linking the two countries as Malaysian Prime Minister Najib Razak played down political uncertainty ahead of a general election to be held this year.

Najib and his Singapore counterpart, Lee Hsien Loong, were on hand as the two countries signed an agreement to build a Rapid Transit System across Singapore's northern edge, with a goal of completion by 2024.

Thousands of Malaysians travel back and forth to tiny but rich Singapore for work and school, and the new transit system is designed to carry up to 10,000 passengers per hour in each direction - more than 30 times more than the existing train service can accommodate.

The two countries are also discussing a separate high-speed rail project, which analysts value at $17 billion - the biggest project undertaken by the Southeast Asian neighbours in recent years.

Singapore was part of Malaysia after the end of British colonial rule but they separated acrimoniously in 1965, clouding diplomatic and economic dealings for decades.

Najib, whose leadership has been mired in a multi-billion dollar corruption scandal at 1Malaysia Development Berhad (1MDB), is hoping to win a third term in a general election due by August, raising questions about the two rail projects. He has consistently denied wrongdoing.

"We cannot determine what the electorate will decide but we can offer our agenda for the people to decide,” Najib told reporters in Singapore when asked about the rail projects.

"We believe they will decide on an agenda that's very meaningful and productive."

Lee expressed confidence that agreements would be honoured by both countries.

As the deadline to award the high-speed project nears, the two states must choose between competing bids from Chinese, Japanese, European and South Korean firms, a decision expected by the end of the year.

Malaysia leans towards China, which has pumped billions into Malaysia over the last two years as Najib looks to tackle massive government debt.

But Singapore's relationship with China has deteriorated over issues such as self-ruled Taiwan, which China considers its own, and disputed South China Sea islands.

The railway is scheduled to be completed by 2026 and will cut the travel time between Kuala Lumpur and Singapore to about 90 minutes from the current four- to five-hour road journey.

The train journey from Singapore to Kuala Lumpur used to take about seven hours before the colonial-era Singapore station was closed in 2011 over sovereignty issues and the track in Singapore was pulled up.